That’s the message from 101 Jewish and pro-Israel organizations that signed on to a letter sent Tuesday to 250 U.S. college presidents and chancellors whose institutions have previously said they reject such boycotts of the Jewish state.

The letter, which was organized by the anti-Semitism campus monitor the AMCHA initiative, refers to recent instances in which faculty members opposed study abroad programs in Israel.

“[I]n light of recent reprehensible attempts by faculty at University of Michigan, Pitzer College and elsewhere to implement an academic boycott that thwarts their own students’ academic freedom and their own colleagues’ scholarly activities, it is imperative that university leaders speak out once again, this time even more forcefully,” the AMCHA letter says.

Among the signers are B’nai B’rith International, NCSY, the Simon Wiesenthal Center and the Zionist Organization of America.

Leadership at both universities has criticized the faculty actions. Pitzer’s president called the vote “inconsistent with Pitzer’s core values” while the University of Michigan sanctioned a professor who refused to recommend a student.